Gasket with electrical isolating coatings

ABSTRACT

An electrically isolating gasket is disclosed wherein a coating layer is disposed on at least one conductive surface, and in some embodiments, on all surfaces or at least all of the conductive surfaces. The electrically isolating gasket includes a core gasket component, a ring seal component, and a non-conductive inner seal component. The coating layer can be, for example, polyimide, polyamide, ceramic, and aluminum oxide.

The present application is a continuation of U.S. patent applicationSer. No. 15/996,975, filed Jun. 4, 2018, which is a continuation in partof U.S. patent application Ser. No. 15/726,080, filed Oct. 5, 2017,through which it claims priority to U.S. Provisional Patent ApplicationNo. 62/404,673, filed Oct. 5, 2016, both of which are herebyincorporated by reference as if set out in full. The present applicationis also a continuation in part of U.S. patent application Ser. No.29/640,610, filed Mar. 15, 2018, the disclosure of which is incorporatedherein by reference as if set out in full.

BACKGROUND

Providing gaskets with electrically isolating properties is desired in avariety of different industries and applications. However, manylimitations exist with respect to previously known gaskets havingelectrical isolating properties.

For example, in some cases, the electrical isolation properties of thesegaskets are not high enough for a given application or industry. Thismay be because the material used to provide electrically isolatingproperties is not a high dielectric material.

In some instances, gaskets with electrically isolating properties arelimited to lower temperature applications because they are not capableof withstanding exposure to high temperatures. In one example, gasketswith electrical isolating properties use glass reinforced epoxy (GRE).However, GRE has a maximum glass transition temperature in the range offrom 250 to 350° F. When gaskets with GRE are exposed to temperaturesabove this range, the GRE becomes soft and rubber-like, and the GREsubsequently lacks the strength to properly support the sealingelements, thus leading to gasket failure. Additionally, GRE is typicallyadhered to a core of a gasket through the use of adhesive. This adhesivemay fail at elevated temperatures and pressures, which can result indelamination.

Many gaskets incorporating materials having electrically isolatingproperties have larger thicknesses due to the material that is added tothe core of the gasket in order to impart electrically isolatingproperties. Many common isolation materials have a dielectric strengthvalue of between 400 and 800 volts/mil. Accordingly, a thick gasket isnecessary to develop enough voltage resistance for common applications.These higher-thickness gaskets result in limitations on where thegaskets can be used.

Other problems associated with previously known gaskets havingelectrically isolating properties include structure complexity, limiteddimensional stability, and limited chemical resistance. Thus, a needexists for an improved gasket having electrically isolating properties.

SUMMARY

Described herein are various embodiments of a gasket having electricallyisolating properties. In some embodiments, the gasket includes a coregasket component having a coating or film of dielectric materialprovided on at least one surface of the core gasket component. In someembodiments, the coating or film comprises polyimide, ceramic, oraluminum oxide. In some embodiments, the coating or film is formed onall surfaces of the core gasket component, including on the surfaces ofany grooves and/or protrusions formed in/on the axial surfaces of thecore gasket component. A core gasket component fully encapsulated by thecoating or film is also described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a gasket according to various embodimentsdescribed herein.

FIG. 2A is a cross-sectional view of the gasket shown in FIG. 1 takenalong line 2-2.

FIG. 2B is a cross-sectional view of a gasket according to variousembodiments described herein.

FIG. 2C is a cross-sectional view of a gasket according to variousembodiments described herein.

FIG. 3A is a top plan view of a gasket according to various embodimentsdescribed herein.

FIG. 3B is a cross-sectional view of the gasket of FIG. 3A along lineA-A

FIG. 3C is a detail of a portion of the cross-section of FIG. 3.

DETAILED DESCRIPTION

With reference to FIG. 1, a gasket 100 having improved electricallyisolating properties according to various embodiments described hereinis illustrated. The gasket 100 generally includes a core gasketcomponent 110 (also referred to as a retainer) and a dielectric coating120 formed on at least one surface of the core gasket component 110(formed on at least the top axial surface of the core gasket component110 as shown in FIG. 1). The dielectric coating 120 may be formed onboth surfaces of the core gasket component 110. The core gasketcomponent 110 may include one or more grooves formed in the axialsurfaces of the core gasket component 110, with each groove having asealing element 130, 140 disposed therein.

The core gasket component 110 can generally have a disc shape such thatthe gasket 100 is suitable for placement between, e.g., flanges ofadjacent pipe segments. The dimensions of the core gasket component 110(e.g., outer diameter, inner diameter, thickness between axial surfaces,etc.) are generally not limited and may be selected based on thespecific application in which the gasket is to be used.

The material of the core gasket component 110 is generally not limitedprovided the core gasket component 110 is suitable for use in a gasket,including meeting or exceeding the properties required for the specificapplication in which the gasket 100 is used. The material of the coregasket component 110 will typically be an electrically conductivematerial because an object of the present application is to provide anelectrically isolating coating to the core gasket component. In someembodiments, the material of the core gasket component 110 is a metal.In some embodiments, the material of the core gasket component 110 isstainless steel.

As noted above, the core gasket component 110 may include one or moregrooves formed in one or more axial surface of the core gasket component110. In some embodiments, the grooves are circular grooves alignedconcentrically with the core gasket component 110, though otherconfigurations can be used. In some embodiments, the grooves formed inone axial surface are identical to the grooves formed in the opposingaxial surface, though other, non-symmetric configurations are alsopossible. In FIG. 1, the core gasket component 110 includes twoconcentrically aligned grooves formed in at least a top axial surface ofthe core gasket component 110, with each groove having a sealing element130, 140 disposed therein.

While grooves are specifically mentioned above and throughout thisdocument, the core gasket component 110 may include raised features inplace of or in addition to grooves. Raised features can be used to, forexample, lock a seal in place or serves as stress concentrators.

With reference now to FIGS. 2A-2C, a cross-sectional view of the gasket100 of FIG. 1 taken along line 2-2 is shown, with each of FIGS. 2A, 2B,and 2C showing a different embodiment of the gasket 100. In FIG. 2A, thedielectric coating 120 is formed on at least one surface of the coregasket component 110; in FIG. 2B, the dielectric coating 120 is formedon at least one surface of the grooves 115 formed in the core gasketcomponent 110; and in FIG. 2C, the dielectric coating 120 is formed onall surfaces of the core gasket component 110, including the surfaces ofthe grooves 115.

While not shown in any of FIGS. 2A-2C, the core gasket component 110 mayalso include one or more features that protrude away from the axialsurfaces 111 of the core gasket component 110. In embodiments where suchfeatures are included, the dielectric coating 120 may be disposed on oneor more surfaces of the raised features.

The specific number of grooves 115 provided in the core gasket component110 is not limited. Furthermore, the cross-sectional shape, depth,width, and placement (e.g., radial distance away from the innerdiameter) of each groove is generally not limited. As shown in FIGS.2A-2C, two grooves 115 are included in each axial surface 111, thegrooves 115 have a generally square cross-sectional shape, the grooves115 are located in close proximity to the inner diameter of the coregasket component 110, and the grooves 115 formed in one axial surfaceare identical in shape, depth, and location to the grooves 115 formed inthe opposing axial surface.

In some embodiments, the grooves 115 formed in the core gasket component110 are used as sealing grooves. These sealing grooves are configuredsuch that one or more sealing elements can be disposed within thesealing grooves 115. Any type of sealing element can be disposed in thesealing grooves 115, including for example E-rings, C-rings, O-rings,and spiral wound-type seals. In some embodiments, and as shown in FIGS.2A-2C, an E-ring 130 can be disposed in the radially outer groove 115and a lip seal 140 can be disposed in the radially inner groove 115.

In some embodiments, the grooves 115 are shaped and dimensioned suchthat only a single sealing element fits within the groove. For example,the radially outer groove 115 can be shaped and dimensioned such that anE-ring disposed therein occupies the entirety of the groove 115 andleaves no additional space for other components, such as a compressionlimiter. The groove 115 can be shaped and dimensioned in this mannerbecause in the embodiments described herein, the gasket retainer (i.e.,core gasket component 110) itself may act as the compression limiter,thereby eliminating the need for a separate compression limitercomponent being incorporated into the gasket 100.

The gasket 100 further includes a dielectric coating 120. As notedabove, the dielectric coating 120 is applied to at least one surface ofthe core gasket component 110, either partially (such as is shown inFIGS. 2A and 2B) or completely covering the surface (such as is shown inFIG. 2C) to which it is applied. As shown in FIG. 2C, in someembodiments, the dielectric coating 120 is applied completely to everysurface of the core gasket component 110, including the surfaces of anygrooves 115 (and/or raised features) formed in/on the core gasketcomponent 110. In other words, the dielectric coating 120 can be formedon the core gasket component 110 so as to fully envelope the core gasketcomponent 110. In this manner, this dielectric coating 120 canelectrically isolate the metallic core gasket component 110 and increasethe range of applications in which the gasket 100 can be used.

In some embodiments, the dielectric coating 120 formed on the one ormore surfaces of the core gasket component 110 is formed with a uniformthickness, including when the dielectric coating 120 is provided on allsurfaces of the core gasket component 110. The thickness of thedielectric coating is generally not limited. In some embodiments, thethickness of the dielectric coating is in the range of less than 6 mm.In some embodiments, the thickness of the coating is 0.381 mm or less,such as 0.127 mm or less.

In some embodiments, the thickness of the dielectric coating 120 mayvary, such as in a scenario where the thickness of the coating on thegroove surfaces (or on raised feature surfaces) is less than thethickness of the coating on other surfaces (axial or radial) of the coregasket component 110. Alternatively, the thickness of dielectric coatingon groove and/or raised feature surfaces can be greater than on theother surfaces of the core gasket component 110. The thickness of thedielectric coating can also vary from groove to groove.

In some embodiments, the dielectric coating 120 is polyimide, polyamide,ceramic, or aluminum oxide, with polyimide being a preferred material.

In some embodiments, the gasket 100, including any coating material, isfree of glass reinforced epoxy (GRE).

The coating 120 may be applied to the core gasket component 110 usingany known technique for applying a coating to a base substrate. In someembodiments, the coating 120 is applied to the core gasket component 110in a liquid form and then cured to form a solidified coating. In someembodiments, the curing is carried out in a continuous manner, whichimproves the throughput of the manufacturing process and makes theprocess more economically feasible. In some embodiments, the continuouscuring process is carried out using a continuous infrared process or bycontinuously passing the core gasket component having liquid coatingdisposed therein through a convection oven. In some embodiments, thecoating 120 is applied directly to the core gasket component 110 withoutthe need for an intermediate adhesive or bonding layer.

The dielectric coating 120 being applied to all surfaces of the coregasket component 110 provides a gasket 100 that is electrically isolatedfrom both any seals used with the gasket as well as from metallic flangesurfaces that the gasket may be disposed between.

In some embodiments, the gasket described herein may further include aninner diameter seal, such as the inner diameter seal described in U.S.Published Application No. 2015/0276105, which application isincorporated herein by reference as if set out in full. Other innerdiameter seals may also be used.

The gasket described herein may be thinner, seal better, improveelectrical isolation, and/or provide a more robust and reliable platformfor fire-safe gaskets than previously known gasket materials. The gasketmaterial described herein also advantageously eliminates any need forglass reinforced epoxy (GRE) in the gasket material. The gasket materialdescribed herein also provides stabilized material thickness andtolerance controls. The gasket material described herein expands theoperating temperatures and electrical resistance of the product andallows for entry into new spaces of development, such as steam andnuclear service. The gasket described herein also expands pressurecapabilities.

The gasket described herein further provides high dielectric strength,permeation resistance, tight tolerance capabilities, impact resistance,strong environmental protection, improved chemical resistance, and asimplified structure (i.e., less components to the overall gasket).

Problems that may be solved and/or advantages that may be achieved bythe gasket described herein include, but are not limited to: improvingelectrical isolation properties of the dielectric components of thegasket through the use of high dielectric material; reducing externalcorrosion through complete encapsulation of the gasket retainer;increasing temperature ranges, allowing for use in wider variety ofapplications where current offerings of isolating gaskets include GRE;eliminating observed problem of failure of adhesive between GRE andretainer material commonly seen at elevated temperatures and pressures;decreasing gasket thickness and thereby allowing for use in a widervariety of applications through the use of thinner dielectric materials,which allows for ease in installation; decreasing the number of gasketcomponents and thereby reducing complexity by eliminating, e.g., abackup ring compression limiting device as what is currently seen insimilar isolating gasket configuration; increasing dimensional stabilitythrough use of materials that have controlled tolerances; increasing theability to hold tight tolerances throughout the manufacturing process;improving sealing performance through the elimination of permeation incurrent gasket facing material as well as providing a more dimensionallystable gasket sealing surface; reducing exposed metal and electricalconduction points by being fully encapsulated in a dielectric material;providing a variety of coatings that can be applied for gasket use in awider variety of applications; providing the ability to vary coatingthickness to accommodate different applications and flange faces;eliminating GRE from the gasket; providing coatings that allow forbetter sealing in the event of exposure to media that is not compatiblewith GRE; controlling gasket colorations to thereby allow for differentcolors to signify different coatings; allowing for use of variedmetallic retainers; metallic retainer coated with dielectric barrierwill continue to act as compression limiter in the event of firepreventing leakage due to loss of stress of the gasket or possibleexpansion and over compression of the seal; non-permeable coatingmitigates explosive decompression in systems where drastic pressurechanges can occur; and; ability to utilize conductive sealing elementssuch as explosive decompression resistant O-rings.

Advantageously, the spray coating of the dielectric material on the coregasket component has provided a thin profile for the resultant isolationgasket, which profile has a thickness or axial height of less than about5 mm, and in some cases less than about 4.7 mm. Disadvantageously,however, gaskets having the thin profile make providing grooves forE-rings, C-rings, O-rings or the like difficult. FIGS. 3A-3C provide agasket 200 that allows for a thin profile but provides an adequateprimary seal and secondary seal without the necessity of grooves to holdadditional seal elements and/or compression limiters.

FIG. 3A shows an elevation view of a gasket 200 with a gasket core 202(or retainer 202). FIG. 3B shows a cross-sectional view of the gasket200. FIG. 3C shows a detail of the cross-section of FIG. 3B. The gasket200 has the gasket core 202, as mentioned above, and an inner sealelement 204. The gasket 200 also has a C-ring 206 interspersed betweenthe gasket core 202 and the inner seal element 204.

The inner seal element 204 is typically formed from a chemically inertmaterial, as well as a non-conducting material. While not to beconsidered limiting, the inner seal element 204 may be formed frompolytetrafluoroethylene (PTFE) or other fluro polymers.

The gasket core 202 and C-ring 206 may be formed from a non-conductivematerial, but typically are formed of a base metal, such as, forexample, stainless steel to name but one possible material. The gasketcore 202 and C-ring 206 may be spray coated with the dielectric materialcoating 120 as described above. The dielectric coating 120 may be any ofa number of materials. In some embodiments, the dielectric coating maybe polyimide, polyamide, ceramic, aluminum oxide, fluoropolymers (suchas, for example, PFA, PTFE, etc), and the like. It has been found thatpolyimide coatings work well for the technology disclosed herein. Thedielectric coating 120 is may be applied as described above.

With reference to FIG. 3C, the gasket core 202 is shown having a firstaxial height of H1. The retaining ring 202 has an inner core surface 208that has a first shape 210. The shape 210 in this exemplary embodimentis a concave shape, which will be explained further below. The innercore surface 208 defines an inner diameter D1 (FIG. 2B) of the gasketcore 202.

The C-ring 206 correspondingly has an outer C-ring surface 212 thatdefines an outer diameter D2. The outer C-ring surface 212 is convex tocooperatively engage the inner core surface 208. Other shapes of theinner core surface 208 and outer C-ring surface 212 are possible. Also,while matching shapes in this exemplary embodiment, the shapes are notnecessarily reciprocal as shown. For example, the C-ring 206 may bereplaced by an E-ring or other convoluted shape seal. The inner coresurface 208 would be designed to wrap around the convoluted outersurface of the seal.

The C-ring 206 comprises an opening 214, which is located opposite theouter C-ring surface 212. The opening 214 defines an inner diameter D3.The C-ring 206 has a pair of seal arms 216 extending from the outerC-ring surface 212 to the opening 214. The seal arms 216 have an apex218. The apex 218, which is shown about midway along the seal arms 216,has an uncompressed height of H2, which is greater than the axial heightH1. When the gasket 200 is compressed between flanged surfaces, the sealarms 216 at apex 218 form a seal interface with the flanged surfaces.Moreover, the opening 214 will decrease in size causing ends 220 of theseal arms 216 to approach each other.

The inner seal element 204, in this exemplary embodiment, is a pressureactivated element where the inner seal element surface 222 provides achevron shape. The inner seal element 204 has an uncompressed height ofH3, which is greater than H2 Other pressure activated shapes arepossible. Also, the inner seal element 204 could have a flat inner sealelement surface in certain embodiments.

The inner seal element 204 also has an outer surface 224 that defines anouter diameter D4, which is substantially the same as the inner diameterD3. An engagement protrusion 226 (or annular ridge 226) extends from theouter surface 224 and extends into the opening 214. Rather than a singleprotrusion 226, the protrusion may comprise multiple legs. Theprotrusion 226 generally has a height that is less than the size of theuncompressed opening 214 such that the protrusion 226 freely fits withinthe opening 214. However, the protrusion 226 could be designed such thata snap fit or friction fit is established between the surfaces 228 ofthe protrusion 226 and the ends 220 of the C-ring 206. When compressed,the ends 220 of the C-ring 206 may grip the surfaces 228 of theprotrusion 226 or, in some instances, pierce the surface 228 to form apositive lock with the C-ring 206.

The inner seal element 204 can be snapped into the C-ring 206 by pushingthe inner seal element 204 until the protrusion 226 plasticly deforms.Once in place, the protrusion 226 would return to its original shape andextend into the opening 214. To facilitate insertion, the inner sealelement 204 may be compressed radially to make the insertion easier. Forexample, the inner seal element 204 may be cooled to condense and shrinkthe diameter of the inner seal element 204. When returned toinstallation temperature (or operating temperature), the inner sealelement 204 would expand as it warms to engage the C-ring 206.

The technology described herein is disclosed in the context of a gasket.However, the same principles can be applied to other types of pipeisolation components. For example, the features described herein,including coating a pipe isolation component partially or fully with adielectric material such as a polyimide, could be applied to the flangesof a monolithic isolation joint, such as the ElectrosStop® MonolithicIsolation Joint manufactured by Garlock Pipeline Technologies, Inc. inHouston Tex.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thescope of the invention. Accordingly, the invention is not limited exceptas by the appended claims.

I/We claim:
 1. An electrically isolating gasket comprising: a coregasket component, the core gasket component having a disc shape with aninner surface defining a first inner diameter; and a ring sealcomponent, the ring seal component have an outer surface shaped tocooperatively engage the inner surface of the core gasket component andan opening opposite the outer surface wherein the opening defines asecond inner diameter that is less than the first inner diameter; anon-conductive inner seal component, the non-conductive inner sealcomponent having an inner surface defining a third inner diameter thatis less than the second inner diameter, the non-conductive inner sealcomponent having an outer surface with a radially extending protrusionshaped to fit within the opening of the ring seal such that thenonconductive inner seal component and the ring seal component arecompression coupled; and a dielectric coating formed on at least thecore gasket component and the ring seal.
 2. The electrically isolatinggasket of claim 1, wherein the core gasket component is made from metal.3. The electrically isolating gasket of claim 2, wherein the metal isstainless steel.
 4. The electrically isolating gasket of claim 1,wherein the ring seal component is made from metal.
 5. The electricallyisolating gasket of claim 4, wherein the metal is stainless steel. 6.The electrically isolating gasket of claim 1, wherein the non-conductiveinner seal component is a fluoropolymer.
 7. The electrically isolatinggasket of claim 6, wherein the fluoropolymer is polytetrafluoroethylene.8. The electrically isolating gasket of claim 1, wherein the core gasketcomponent has a first height and the ring seal has a second heightgreater than the first height.
 9. The electrically isolating gasket ofclaim 8, wherein the non-conductive inner seal component has a thirdheight greater than the second height.
 10. The electrically isolatinggasket of claim 9, wherein, wherein the coating material is polyimide.11. The electrically isolating gasket of claim 10, wherein the coatinghas a uniform thickness.
 12. The electrically isolating gasket of claim11, wherein the thickness is less than 0.381 mm.
 13. The electricallyisolating gasket of claim 12, wherein the thickness is less than 0.127mm.
 14. The electrically isolating gasket of claim 1, wherein the innersurface of the non-conductive inner seal component forms a chevronshape.
 15. The electrically isolating gasket of claim 4, wherein thering seal comprises a pair of seal arm extending from the outer surfaceto the opening such that the pair of seal arms have an apex between theouter surface and the opening such that the seal arms form a sealinterface with opposed flanged surfaces.
 16. The electrically isolatinggasket of claim 15, wherein the ring seal is selected from one of anE-ring or a C-ring.
 17. The electrically isolating gasket of claim 1,wherein the radially extending protrusion comprises a plurality ofradially extending protrusions.
 18. A method of manufacturing anelectrically isolating gasket comprising: coating every surface of aconductive core gasket component with a liquid coating of dielectricmaterial and continuously curing the liquid coating to harden the liquidcoating and secure the coating to the disc-shaped gasket component;coating every surface of a conductive ring seal component with a liquidcoating of dielectric material and continuously curing the liquidcoating to harden the liquid coating and secure the coating to thedisc-shaped gasket component; and assembling an electrically isolatinggasket by fitting the ring seal component within an inner diameter ofthe core gasket component and fitting a non-conductive inner sealcomponent within an inner diameter of the ring seal component.
 19. Themethod of manufacturing an electrically isolating gasket of claim 18,wherein continuously curing the liquid coating comprising continuouslyexposing the liquid coating to infrared radiation.
 20. The method ofclaim 19, wherein fitting non-conductive inner seal component within aninner diameter of the ring seal component comprises cooling thenon-conductive inner seal component to shrink a diameter of thenon-conductive inner seal component.